We just had it on a rolling road and established that we weren't getting locked in wheel speed until about 5,600 - 5,700 rpm when the cam is nearly done and we've missed it's peak torque, 306hp to the rear wheels.

I believed at the time I bought the converter that due to it being a light vehicle I needed a higher stall converter hence the purchase but I suppose I was wrong. I know it's a very basic cam and converter mismatch now.

Comp Cam recommend a 2,800+ stall and I suppose my question is, if I got a 2,800 or so stall do you reckon I'd still get an extra 500 rpm flash out of it like my current converter meaning I really need a 2,300 stall for that cam? Or is my current converter misbehaving? It was only a cheapest Boss Hog converter.

One mate said slot in a standard converter since it's a light car but I don't agree, having said that I've just got myself confused with the weight thing I think

The weight of the car is irrelevant to what the converter flash stall speed at launch is going to be.
(Assuming you got traction.)
You got the right converter but the wrong cam. Get rid of the sissy (Hyd) cam.

Swap to a Isky Cams 201CC1 or 201547 or 201549 Be sure to use suitable correct valve springs.
Now the tunnel ram can work.

Further: If the goal is to go faster in the 1/4 mile then this car does not have enough gear ratio.

The gear ratio needs to be high enough so that at the top end of the track the engine rpm is about 2000 rpm HIGHER rpm than the stall speed seen at launch ( "flash stall speed)

That means you want o be trapping at about 7000rpm.

At 2100 lbs and 306 chassis dyno HP the car should go 118 to 122 MPH.
Correct gear will be about a 4.56 gear for this.
Now the car will go a lot quicker and the converter will function correctly
with about a 7 percent coupling % at high rpm thru the traps.

The stall speed will be the same but the car performance will be a lot better.
One of the Isky cams listed will give the engine the top end rpm capability and power to
trap at 7000rpm. The engine power curve will be a LOT Better with more HP
and the car will fly.

Put the new cam in and take the car to the track and run it.
What is the trap speed and engine tach rpm thru the traps?

The speed will be about 122 MPH +/- and the engine max rpm will be a bit too LOW.
(remember you want the max engine rpm at the top end about 2000 rpm HIGHER than your flash stall speed rpm)
Now change the gearing for this. The power glide needs correct gearing.
The converter will work like you never seen and the car will go better too.

It will then "drive" better on the street too.

if the dyno test is accurate and car weight is accurate I predict a 4.56 gear is right.
Small difference will still want the same gear.

Ditch the sissy rabbit hyd cam for one of the Isky solids and gear the car correctly
based on track MPH and engine trap rpm and it will FLY.
( gear it to trap at about 7000 rpm) 3.91's is wrong.

And it will "drive" great around town too.

(Take note: Even if you change the converter, the 3.91's will still not be right.
This car needs to trap at about 7000rpm. correct gears will give you this.
The power glide is very critical on getting the correct gearing.
When the gearing is correct for the car the converter performs as designed too.
So......)

Last edited by F-BIRD'88 on Tue Oct 17, 2017 4:31 pm, edited 1 time in total.

You are confusing the initial "flash stall speed" at launch with how the converter loads and operates at high road speed and high engine rpm and how it "couples" and where on the track it is going to "lock up"
This is the point where it stops being a Torque converter and becomes a "fluid coupling". and no longer is multiplying torque ("stall mode")
The stator in the converter is no longer stationary and spins at more or less engine rpm.
This point of down track "lock up" ( which is never 100% 1 to 1) is a function of car weight and gear ratio and wind resistance too.

But this is not "stall speed" and you will not get it right until the car's rear axle gear ratio is correct.
Right now the car is under geared. Many trans/ converter guys do not understand how this all works.
get the 1/4 mile trap rpm about 2000 rpm HIGHER than the observed launch stall speed is and it will be about right and the converter will work as designed and intended. and "lock up"

Flash stall speed is a function of engine torque input.

(Even if this is just a street car-hot rod) take the car to the track and tune it for best 1/4 mile track MPH.
With that 1/4 mile track MPH info and the ENGINE RPM seen at the finish line you can then calculate the
correct axle gear ratio to get the engine trap rpm correct .

(with the 391's and 27.5" tires) the trap rpm will be too low.
Now -re gear the car to 1/4 mile "trap" at or real close to 7200 rpm..

Thus the need for a solid lifter cam like the Isky solid cams listed.
The car, engine (with tunnel ram) and trans/5000 stall converter will be very happy and the car will GLH and drive way better too.
The "5000 stall" torque converter will suddenly "lock up" and "couple" and perform like intended.

This rough But accurate guideline rule of about a 2000 rpm spread between the real on track Launch flash stall speed and the engine rpm thru the traps (1/4 mile) is always Very close to correct.

The vehicle weight has to affect stall speed & flash stall. Extreme example, but imagine if the car weight was 10,000 lb; more tq will be needed to move it from rest, & that is going to result in more c'ter slippage to get the needed tq....& higher stall speeds.

If you take a set of 4.56's out and change to 5.38's (for example), the convertor 'flash' will be lower as the car moves easier with the 5.38's. Same with transmissions...a change from a 2.08 low gear to a 2.75 will result in a lower 'flash' rpm.